Pip machine



NOV. 3, 1970 sc ETAL PIP-MACHINE Filed Oct.28, 1966 STA.B A 34 35 27 STA.A I, 2

HERBERT N. FELIX 2 Sheets-Sheet 1 FIG.|

INVENTOR SCHL IN BROWN BY W 1 ZZZ/z ATTORNEYS Nov. 3, 1970 H. N. SCHLEIN ETAL 3,537,786

7 PIP MACHINE I Filed Oct'. 22. 1966 I 2 Sheets-Sheet 2 F 3 NVEN'I'ORS 1 HERBERT N. SCHLEIN BYFELIX H. BROWN ATTORNEYS United States Patent Int. Cl. G03g 15/22 US. Cl. 355-3 17 Claims ABSTRACT OF THE DISCLOSURE A copying machine utilizing material capable of being persistently internally polarized as the latent image storage means. A removable insulative carrier is applied to the storage means and receives a toner which clings to the carrier in correspondence with a previously applied image pattern. The carrier is then removed from contact with the storage means and forms a record of the recorded image. In one embodiment, the insulative carrier is then passed over a heater to fix the toner so that the insulative carrier forms the final image bearing means. In an alternative embodiment the insulative carrier bearing the toner is brought into contact with a separate image bearing media so as to transfer the toner to this image bearing media which then acts as the final image bearing means.

This application is a continuation-in-part of United States patent application, Ser. No. 445,910 filed Apr. 6, 1965, and Ser. No. 534,697 filed Mar. 16, 1966.

This invention relates in general to image forming processes and more particularly to a machine and methods for forming and reproducing images.

A typical prior art method and machine which has been useful for image transfer or reproduction is known as xerography. This process comprises the steps of uniformly spraying electric charges on the surface of a photoconductive layer by means of a corona discharge. Following this establishment of a uniform charge on the surface of the photoconductive layer, the image to be reproduced is formed on the layer surface by means of selectively discharging areas of the surface. This selective discharge, which must be accomplished within a few moments of the establishment of the charge, occurs when the layer is exposed to light. This light causes the exposed areas of the layer to become photoconductive thereby permitting a substantial leakage of surface charges through the layer to ground. Since the unexposed areas of the layer remain nonconductive, the charge on the unexposed areas of the surface remain in place.

Following this selective discharge of surface charges, there is deposited on the surface an electroscopic powder that assumes the form of the image through electrostatic attraction and that can be readily transferred thereafter from the surface to a sheet of suitable material, such as paper, and fused thereto.

Apparatus utilizing the above image forming technique have a number of drawbacks in that the photoconductive layer is expensive to produce and requires special preparation. Further, as is well known, the corona discharge establishing the surface charge requires DC voltages on the order of 6 to 10 kilovolts. Still further, such machines require 200 watt power supplies. Additionally, because the charges utilized in such an electrophotographic process are surface charges, the machines are humidity sensitive. That is, high humidity conditions can cause the surface charges to leak off prematurely or prevent the establishment of adequate surface charges. Furthermore, these machines cannot produce multiple copies from a single 3,537,786 Patented Nov. 3, 1970 exposure. Moreover, these machines as presently sold have difficulty in obtaining continuous tone gradations, and thus do not provide quality photographic reproductions. Additionally, such machines because of inherent limitations in the electrophotographic process cannot be used to produce color images by simultaneously applying at least two different colors to the charge pattern.

The above difficulties and disadvantages found in the xerographic machines and processes are overcomes by the PIP machine described in US. patent applications Ser. No. 445,910, filed Apr. 6, 1965 and Ser. No. 534,697 filed Mar. 16, 1966. The PIP machines described therein exploit the phenomena known as Persistent Internal Polarization. This phenomenon, hereinafter called PIP, exists in certain photoconductive insulators dispersed in selected dielectric media and is produced by placing the loaded di electric in an electrical field during or shortly after light exposure whereby an internal polarization is created in the material.

The basic PIP copying machine described in the above- Inentioned basic applications is comprised of (1) a latent image storage means, (2) means for irradiating and applying an electrical field to the storage means to uniformly internally polarize the storage means, (3) means for impressing an image in the storage means by selectively discharging areas of the internal polarization therein, -(4) means for dispensing on the surface of the storage means toner capable of being attracted to the field due to the polarized areas of the storage means, (5) means for transferring the toner from the storage means surface to a transfer medium, and (6) means for transporting the stoage means past each of the other means.

Although to the casual observer there appears to be identity between the electrostatic phenomenon previously described as the basis of xerography and the polarization phenomenon known as PIP, there are significant external differences and the underlying physical mechanisms are fundamentally dissimilar and distinct. These differences and distinctions are what give rise to the advantages of the PIP machine, for example, the ability to produce quality, continuous tone reproductions without requiring high voltages or expensive and difiicult-to-produce mate rials. Further advantages of the PIP machine include its insensitivity to humidity, the capability of producing multiple copies from a single exposure and the further capability of producing color images by the simultaneous application of at least two different color toners. Additionally, the resolution of the copies produced by the PIP machine may be varied to meet the requirements of the use as distinguished from the copies produced by the prior art machines Whose resolution is fixed.

The preferred embodiment of the PIP machine described in the above-mentioned basic applications utilize, as a latent image storage means, a rotatable drum comprised of a PIP material which is supported on a conductive member and covered by a layer of transparent insulating material in the form of a continuous unbroken film covering the circumference of the PIP material. The use of such an insulative layer minimizes both the distortion of the polarization pattern within the PIP material and the damage to the PIP material, both of which phenomena would otherwise result from the closeproximity or contact of the PIP material with the field applying electrodes used in the uniform polarization, image impressment and toner transfer steps. While the cause of the distortion is not yet fully understood, it is believed to result from an electrostatic attraction between the electrodes and underlying PIP material which cause some kind of migration or alteration of the charge pattern when the electrode is removed. Use of an insulative layer overlying the PIP material and separating itfrom .the electrodes minimized alteration of the polarization pattern within the PIP material and, incidentally, increased both the persistence of the polarization pattern and the degree of polarization attainable. Furthermore, abrasion of the PIP material resulting from the electrostatic attraction of the PIP material to the electrodes was almost entirely eliminated by use of the insulative layer.

Notwithstanding the improvements in the basic PIP machine resulting from use of such an insulative layer, several distinct and different difficulties remained. One major problem involved the undesirable build-up of electrostatic charges on the insulative layer during operation of the machine. This electrostatic build-up, believed to result from primarily the use of high voltages during the toner transfer step, partially masked or altered the true image pattern residing in the PIP layer, thereby reducing the fidelity and resolution of the toner image on the transfer paper, especially when the machine was used as a multiple copier, that is a machine for making several copies of an image from a single exposure. Several methods of reducing this electrostatic build-up were described in the abovementioned applications. One of the most effective methods involved the use of lower voltages in the toner transfer step. The use of lower voltages, however, reduced somewhat the completeness of the toner transfer. Especially when a number of copies were to be made from a single image exposure, in order to overcome the natural decay of the latent image in the PIP material and produce copies of constant toner density, it was desirable to increase the transfer voltage for successive copies being made from a single image exposure. Accordingly, it was necessary to arrive at a compromise transfer voltage for each copy which took into account both the deleterious effect of a higher transfer voltage on the faithfulness and resolution of the image reproduction and the desirable effect of a higher transfer voltage on the toner density of the copy.

The other major problem with the PIP machine was entirely distinct from the requirement of a compromise toner transfer voltage. As expected, the toner image on the transfer paper, produced by transferring toner from the latent image storage means onto the transfer paper and fusing it thereto, was inferior in terms of resolution to that produced by the direct fusing of toner onto the latent iamge storage means. While the loss of resolution resulting from the use of a toner transfer step was not as great as to diminish the utility of the PIP machine as a standard office copier, it did hamper the adaptation of PIP machine techniques to more esoteric applications, such as the creation of slides, transparencies, microfilm and other items suitable for projection or magnification. On the other hand, fusing of toner onto the latent image storage means was commercially impractical in view of the high cost of the available PIP materials.

Another difficulty encountered with the PIP machines arose out of the time required for discharge of the electrostatic charge build-up previously referred to. The alternative solutions here were either slower copying rates or larger and thus more costly, storage means.

A serious disadvantage of the PIP machines was the high cost of replacing the latent image storage means element. While use of the insulative layer increases the use ful life of the underlying PIP layer, the insulative layer itself had a limited useful life and replacement of the inexpensive insulative layer required replacement of the entire storage means, including the relatively expensive PIP medium. A further disadvantage lay in the elaborate precautions required to insure that, during the toner trans fer step, toner did not accidentally land on the area of the latent image storage means where it would subsequently interfere with the accuracy of the subsequent image transfers made therefrom.

The present invention avoids the above difficulties and disadvantages found in the PIP machines disclosed in the basic applications by providing embodiments of the present invention wherein the use of higher toner transfer voltages does not deleteriously affect image reproduction, and wherein projection quality copies may be produced at a commercially practical cost on copy paper having any desired degree of transparency or opacity.

Further, the present invention permits a more complete discharge of the electrostatic build-up on the insulative material without diminishing the copy rate of the machine or increasing the size of the latent image storage means.

Furthermore, the present invention increases the useful life of the PIP material by permitting replacement of the insulative material alone and minimizing the possibility of random toner being deposited upon the latent image storage means during the toner transfer step.

Briefly, the present invention accomplishes these objects and purposes through use of an insulative carrier which is not a part of the latent image storage means, and which need be in physical contact with the PIP medium only during the toner dispensing operation.

Other objects and features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawing wherein:

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention providing for a toner transfer step at a location removed from the latent image storage means;

FIG. 2 is a cross-sectional view of an embodiment of the invention wherein the toner is permanently fixed on the insulative material, and

FIG. 3 is a cross-sectional view of an embodiment of the present invention wherein the insulative material contacts the latent image storage means only tangentially.

Throughout the several figures of the drawing, like reference numbers will be used to designate like components. Furthermore, the lettering of stations and the numbering of elements functionally similar to those described in the basic applications will correspond to the station letters and element numbers used therein. For purposes of clarity, the embodiments have been represented schematically in the drawing; while all structural details have been omitted from the drawing, these can be readily supplied by the utilization of prior art techniques.

With reference to the drawing, FIG. 1 shows a carrier 25 of insulative material in the form of an endless loop. The carrier 25 is removably situated about a rotating latent image storage means and a rotating conductive cylinder 101 for travel therewith. The storage means 100 comprises a rotatable conductive drum 20 on which are supported a plurality of segments 21 composed of a material exhibiting the PIP phenomenon. It is similar to those storage means shown and described in the basic applications save in the following important respect: instead of the insulative material being an integral part of the storage means and constituting the circumference thereof, in the instant embodiment the insulative material is in the form of an endless loop carrier 25 in contact with only a portion of the circumference of the storage means 100 at any given instant.

The PIP segments 21, as indicated in the basic applications, are composed of photoconductive insular particles 22 dispersed in a matrix or binder 23 having a volume resistivity greater than 10+ ohm-cm. The insulative carrier 25 is composed of material having, in addition to the characteristics described in the basic application, a modulus of elongation, tear strength, flexibility and other physical properties appropriate for its use as an unsupported entity, distinct and apart from the storage means. Among the suitable organic materials are polyethylene, polypropylene, polyethylene glycol terephthalate (Mylar), poly-tetrafluoroethylene (Teflon), polyvinylidene-acrylonitrile copolymers (Saran), cellulose nitrate, cellulose acetate, acrylonitrile-butadienestyrene terpolymers, cyclicized rubbers and similar irradiation-transparent, essentially non-photo-polarizable organic or inorganic materials having a volume resistivity greater than ohm-cm. Of these, polythylene glycol terephthalate (Mylar) is the preferred material for use as original or replacement insulative carriers.

Stations A, B and C are similar to those described in the basic applications. Station A provides means to irradiate and apply a uniform unidirectional electrical field to the PIP material to internally uniformly polarize the PIP material; Station B provides means to impress in the PIP material a radiation image consisting of a pattern of radiation and non-radiation to selectively modify the polarity of areas of the uniformly internally polarized PIP material; and Station C provides means to dispense, on the surface of the insulative carrier or insulative layer, a toner capable of being attracted to the field due to the underlying internally polarized areas of the imaged PIP material.

Station A is adapted to apply uniform irradiation and uniform unidirectional electrical fields to the storage means 100 either simultaneously, as by means of the NESA tube 26 shown in FIG. 1, or sequentially, as by means of a light source 27 followed by a voltage applying electrode 28 as shown in FIG. 2. Referring now to the embodiment of FIG. 1, which utilizes the simultaneous application technique, the NESA tube 26 contains an elongated ribbon filament 27 and has on its exterior a thin, transparent conductive coating 28.

Station B impresses the image, represented by the arrow 34 on the far side of the optical scanning system or lens 33, either by means of selective irradiation alone, or by means of a combination of selective irradiations and a uniform unidirectional electrical field applied by an electrode 37. As with Station A, the irradiation and electrical field of Station B may be applied to the storage means either simultaneously or sequentially, that is, with the irradiation field preceding the electrical field. In the embodiment shown in FIG. 1, the simultaneous application technique is utilized and thus the electrode 37 must be transparent to the irradiation.

Station C is adapted to dispense one or more charged toners 42 from the bottom opening 44 of a trough-shaped hopper 41, the hopper 41 being suspended over the Width of the underlying insulative carrier 25 by means of the interaction of the charged toner particle 48 and the particular underlying area of the PIP medium having a predetermined attracting polarity-either the original or reversed PIP. Thereafter the dispensed toner 48 tends to remain in place unless disturbed.

After a given insulative carrier segment 25 overlying a given storage means area 21 passes through Station C, the rotating cylinder 100 draws the toner-bearing insulative carrier segment 25' towards it, thereby breaking the physical contact between the insulative carrier segment 25' and the storage means area 21. The insulative carrier segment 25' is then drawn to Station D where the toner 48 is transferred to a medium suitable for permanent toner retention, such as a paper sheet 49, fed into appropriate position by a rotating conductive drum 50. The operation performed at Station D of this embodiment is similar to that performed by Station D of the basic applications, the minor structural differences being that the instant Station D, as shown in FIG. 1, creates a voltage differential between the conductive drum 50 and the conductive cylinder 101 rather than between the conductive drum 50 and the conductive member within the storage means.

However, because the toner transfer operation of the instant Station D occurs at a location far removed from the location of the storage means 100, one need not consider the effects of higher transfer voltages in creating an electrostatic charge build-up within the insulative carrier 25. As the storage means 100 and Station D may be separated by any desired distance, additional time may easily be afiorded for discharge of any such electrostatic charge build-up on the insulative carrier 25 without any diminution in the number of copies which may be made in a given unit of time and without any increase in the size of the storage means. Accordingly, the esoteric devices described in the basic applications for reducing electrostatic charge build-up, for example, use of a radioactive source and a grounding roller, may be dispensed with. If desired, the conductive drum 50 may be of the type indicated in the basic applications but not shown herein; that is, a conductive roller slightly displaced from and to the rear of the transfer paper 49 and supported on the insulative carrier 25 or the cylinder 101 by means of thin, insulative shoulders. In either case, it will be noted that the toner transfer operation is performed at a location removed from the storage means, thereby minimizing the possibility of toner accidentally escaping o o the storage means for Station D.

Once the insulative carrier segment 25 has passed through Station D, the rotating storage means pulls the insulative carrier segment 25 towards it, thereby breaking contact between the cylinder 101 and the insulative carrier segment 25' and drawing the insulative carrier segment 25' onto the storage means 100.

After the toner transfer step at Station D, any residual toner remaining on the insulative carrier segment 25' may be removed, as by brushing the surface thereof with a brush 52. It will be noted that, as the residual toner is not at this point held to the insulative carrier segment 25' by means of underlying areas of polarity, one may dispense with the Station E required in the machines described in the basic applications for the purpose of discharging the residual internal polarization of the storage means prior to brushing.

In order to transport the storage means segments 21 past Stations A through C, the insulative carrier 25 over the storage means 100 and cylinder 101, and the transfer paper 49 about the drum 50, it is preferred that the storage means 100, cylinder 101 and drum SO-each'be driven at an appropriate rate of speed; however the same purposes may be effected with less than all of such elements being driven and the remainder of the elements acting as idlers.

Whereas the embodiment previously described and illustrated in FIG 1 will, for convenience, be referred to as a machine based on an indirect process because a toner transfer step is required, the embodiment to be described below and illustrated in FIG. 2 will, again for convenience, be referred to as a machine base on a direct process because no toner transfer step is utilized, the toner applied to the insulative carrier of the direct embodiment being permanently maintained thereon.

The direct embodiment is fundamentally similar to the indirect embodiment with respect to the storage means 100 and the Stations A through C. Instead of being in the form of an endless loop, however, in the direct embodiment the insulative carrier 25 is in the form of a flexible sheet, fed onto the storage means 100 from a supply drum 102 and taken off the storage means by a take up drum 103.

Referring now to both FIGS. 1 and 2, Stations A, B and C of the direct embodiment are the substantial functional equivalents of their counterparts in the indirect embodiment. To indicate the available option, however, Stations A and B of FIG. 2 have been shown utilizing the sequential technique earlier described for applying irradiation and electrical fields rather than the simultaneous technique shown in connection with Stations A and B of FIG. 1. In point of fact, the Stations A and B represented in FIG. 1 are freely interchangeable with the Stations A and B represented-in FIG. '2, the selection of the concurrent or sequential techniques being a matter of choice as indicated in the basic application. Station C is identical in both embodiments.

In the operation of the preferred direct process embodiment, an insulative carrier segment 25', drawn from the supply drum 102, is placed in direct physical contact with the storage means surface area 21. The storage means area 21' underlying the insulative carrier segment 25 is then uniformly polarized at Station A by means for applying a uniform irradiation field and a uniform unidirectional electrical field. The insulative carrier segment 25' and underlying storage means area 21 are then drawn to Station B where a latent image is impressed, through the insulative carrier segment 25', upon the storage means area 21. The insulative carrier segment 25' and underlying storage means area 21' are then drawn to Station C where a charged toner 42, applied to the surface of the insulative carrier segment 25, is attracted to the field due to the internal polarization of portions of the underlying storage means area 21. The take-up drum 103 then draws the toner-bearing insulative carrier segment 25' away from the storage means area 21' and stores it for later use.

If the toner 42 applied at Station C is liquid, the time of travel required for the toner-bearing insulative carrier segment 25 to pass from Station C to the take-up drum 103 should be sufiicient to allow for drying of the applied toner 48. If desired, a drying element such as a heating element 104 may be positioned between Station C and the take-up drum 103, adjacent to the path of travel of the toned surface to hasten the drying. If the toner 42 applied at Station C is solid, suitable means for fusing the applied toner 48 onto the toned surface should be provided between Station C and the take-up drum 103; for example, a heating element 104 adjacent to the path of travel of the toned surface. If desired, the fused toner may be cooled prior to roll-up by any of the conventional techniques well known in the art, for example, a forced draft of cooling air.

Travel of the insulative carrier segment 25' from the supply drum 102, through the various Stations A, B, C, any heating element 104, and onto the take-up drum 10-3 may be accomplished by driving the take-up drum 103 while permitting the storage means 100 and supply drum 102 to act as idlers. Alternatively, the take-up drum 103 and the storage means 100 may be driven; and, especially if the insulative carrier 25 is susceptible to stretching or tearing, the take-up drum 103, the storage means 100 and the supply drum 102 may each be driven at appropriate speeds to prevent the creation of stress in the insulative carrier 25.

While the embodiment illustrated in FIG. 2 is especially useful in the production of microfilm and other materials usually stored on a drum, it will be obvious to those skilled in the art that the processed insulative carrier stored on the take-up drum may be removed therefrom and cut into projection slides, transparencies and other items usually used in discrete units. It will further be obvious to those skilled in the art that if discrete units are desired, the take-up drum may be eliminated, in which case the processed insulative carrier may be drawn by rollers from the storage means and immediately cut into discrete units suitable for use as transparences or projection slides.

Transparency to irradiation has been one of the essential requisites posited for the insulative layers of the basic applications as well as the insulative carrier of the above-described embodiments of the present invention. It will be noted, however, that this requirement is avoided in the embodiments of the present invention described below. While it is essential that the insulative carrier segment 25' and the corresponding underlying storage means area 21 being operated upon at Station C be in physical contact as they both pass through Station C, this requirement does not hold for Stations A and B. If desired, Station A, Station B or both Station A and B may be situated so as to operate directly on the storage means; for example, in both FIGS. 1 and 2, Stations A and B may be located about the bottom half of the storage means 100 between the points where the insulative carrier 25 breaks and makes physical contact with the outer circumference of the storage means 100. As in this embodiment the irradiation need never pass through the insulative carrier 25, the latter may be opaque to the irradiation used, and in fact may simply be ordinary paper of suflicient resistivity.

While the option of using an opaque insulative carrier in connection with the indirect embodiment will afford certain advantages, the prime utility of the option is realized in connection with the direct embodiment, which may then be used not only to produce projectable transparencies but also opaque copies having the appearance of ordinary paper.

Referring now to FIG. 3, the elements of the direct embodiment of the present invention there represented are substantially identical to those in the direct embodiment represented in FIG. 2 except that, instead of the supply and take-up drums 102 and 103, the embodiment of FIG. 3 uses idling or driven rollers 105 to apply the insulative carrier 25 to the storage means and remove it therefrom. Although the insulative carrier 25 is shown as only tangentially contacting the outer circumference of the storage means 100, obviously it is also possible, by an adjustment of the position of rollers 105, to provide for curving the insulative carrier 25 thereabout to thereby provide a longer contact time between the insulative carrier 25 and the storage means 100.

As indicated above, any or all of the minor modifications or specialized techniques described in the basic applications may be adapted for use in conjunction with the present invention. For example, where impressment of an image at Station B results in the storage means having both areas which retain the initial polarization impressed at Station A and also areas which acquired a reverse polarization at Station B, two oppositely charged toners may be dispensed at Station C, one capable of being attracted to carrier surface areas having the initial polarization, the other two areas having the reverse polarization. In this manner a two-tone or color transparency may be produced. Also means may be provided for deactivating Stations A and B once a latent image has been formed in the storage means, so that multiple copies of the same latent image may be produced by continued operation of the machine with only the remaining Stations being activated.

While, for convenience, each embodiment has been represented in the drawings in a particular spatial orientation, it is to be understood that each embodiment may be used in other spatial orientations. For example, the embodiment of FIG. 1 may be used in an orientation turned ninety degrees from that shown in the drawings, so that traverse of the toner-bearing insulative carrier from Station C to Station D is horizontal. Stations C and D may also be brought closer together on one side of the horizontal traverse path to further insure that toner dispensed at Station C is not unintentionally displaced from its initial position on the insulative layer by gravitational forces. The degree to which the interference of gravitational forces must be considered will, of course, depend on the particular type of toner used and the forces which secure it in place on the insulative carrier surface in the absence of underlying PIP. It will also be understood that the dimensions of the various elements of the device may be modified either uniformly or with respect to one another; for example, cylinder 101 may be modified to have a diameter greater or less than that of storage means 100.

While one aspect of the invention resides in the laminar combination of a latent image storage means having a medium displaying PIP and a removable insulative carrier covering in part the surface of the medium and in contact therewith, the radiation transparency specification of the insulative carrier will be determined by the process conditions under which the combination is to be used. In certain instances, the insulative carrier may desirably be transparent to electromagnetic radiation in the visible spectrum; that is, light having wavelengths in the range of 4,000 to 7,000 angstrom units; in other instances, the insulative carrier may desirably be opaque or translucent to such radiation.

Now that several preferred embodiments of the present invention have been described, other embodiments may readily become apparent to those skilled in the art. It is therefore understood that the true spirit and scope of the present invention is limited only by the scope of the appended claims.

What is claimed is:

1. A copying machine comprising an insulative carrier means,

a latent image storage means comprising a medium capable of being internally polarized by the application of radiation and an electrical field,

means for removably applying a segment of said carrier means to the surface of a segment of said storage means for movement therewith,

means for irradiating and applying a uniform unidirectional electrical field to said storage means segment to internally uniformly polarize said storage means segment,

means for impressing an image in said uniformly polarized storage means segment by selectively modifying the internal polarization of portions of said uniformly polarized storage means segment,

means for dispensing on said carrier means segment overlying said image-bearing storage means segment a toner capable of being attracted to the field due to the underlying portions of said image-bearing storage means segment having a predetermined internal polarity,

means for removing said toner-bearing carrier means segment from said image-bearing storage means segment.

2. The copying machine of claim 1, further having means for fusing said toner to said removed carrier means segment.

3. The copying machine of claim 1, further having means for transferring said toner from said removed carrier means segment to a medium suitable for retention of said toner.

4. The copying machine of claim 1 wherein said carrier means is transparent.

5. The copying machine of claim 1 wherein said carrier means is not transparent to said irradiation and said segment applying means applies said carrier means segment to said image-bearing storage means segment.

6. A copying machine comprising a latent image storage means, said storage means comprising a first conductive member and a medium supported thereon capable of being internally polarized by the application of radiation and an electrical field;

first means for removably applying an insulative carrier over the exposed surface of said medium, in substantially parallel relationship to said exposed surface and for movement therewith;

second means for uniformly irradiating and applying a uniform directional electrical field to said medium to uniformly internally polarize said medium, said field applying means having a power supply and a second conductive member in substantially parallel relationship to said first conductive member with said medium and said insulative carrier maintained therebetween;

third means for applying a second uniform directional electrical field and a selective radiation pattern to said medium, said field applying means having a power supply and a third conductive member in substantially parallel relationship to said first conductive member with said medium and said insulative carrier therebetween, said second field having a polarity opposite to said first field to selectively reverse the internal polarization of the areas of said medium irradiated by said pattern;

fourth means for dispensing a charged toner on the exposed surface of said insulative carrier, said toner being attracted to the field due to said reversely polarized areas of said medium;

fifth means for removing said insulative carrier from said medium; and

means for transporting said storage means past said enumerated means.

7. The copying machine of claim 6 including sixth means for transferring said toner from said removed insulative carrier, at a point removed from said medium, to a body suitable for permanent retention of said toner, and seventh means for removal of residual toner from said removed insulative carrier.

8. The copying machine of claim 6 including sixth means for fusing said toner onto said removed insulative carrier at a point removed from said medium.

9. The copying machine of claim 6 wherein said fourth means dispenses two charged toners, one of said toners being attracted to the field due to the remaining initially polarized areas of said medium and the other of said toners being attracted to the field due to the reversely polarized areas of said medium.

10. The copying machine of claim 6 wherein said insulative carrier is transparent.

11. A copying machine comprising a latent image storage means comprising a medium capable of being polarized by the application of radiation and an electrical field;

means for uniformly irradiating said storage means and for applying a uniform directional electrical field to said storage means to internally uniformly polarize said storage means;

means for subjecting said storage means to a radiation image consisting of patterns of radiation and nonradiation to selectively discharge polarized segments of said storage means;

means for applying an insulative carrier on a surface of said storage means;

means for dispensing charged toner on the exposed surface of said insulative carrier overlying said storage means, said toner being maintained on said surface by interaction with the underlying segments of a predetermined polarity in said storage means;

means for removing said insulative carrier from said storage means;

means for fusing said toner onto said insulative carrier, at a point removed from said storage means for permanent retention of said toner;

means for transporting said insulative carrier past said carrier-applying means, said dispensing means, said carrier-removing means and said fusing means and for transporting said storage means past said uniformly polarizing, imaging and dispensing means.

12. The copying machine of claim 11 wherein said insulative carrier is non-transparent to said radiation image.

13. The copying machine of claim 11 including means for deactivating said uniform polarizing and image impressing means whereby multiple copies may be produced from a single image exposure.

14. A copying machine comprising:

a rotatable cylindrical latent image storage means, said storage means comprising a medium capable of being internally polarized by the application of radiation and an electrical field;

a rotatable cylinder displaced from said storage means and axially parallel thereto;

an insulative carrier in the form of an endless belt looped about said storage means and said cylinder for travel therewith;

means about said storage means for impressing an image in said storage means by selectively internally polarizing segments of said storage means;

means about said storage means for dispensing on a segment of said carrier a toner capable of being attracted to the field due to the underlying segments of said storage means having a predetermined polarity;

means for transferring said toner from said carrier segment, at a location removed from said storage means, to a medium suitable for retention of said toner; 1

means for rotating said storage means segment past said impressing and dispensing means and for trans porting said carrier segment past said dispensing means while said carried segment is in contact with said storage means segment and past said transfer means while said carrier segment is displaced from said storage means segment.

15. The copying machine of claim 14 wherein said transfer means transfers said toner from said carrier segment to said medium suitable for retention of said toner while said carrier segment is in contact with said cylinder.

16. The copying machine of claim 14 wherein said insulative carrier is transparent and wherein said transport means transports said carrier segment past said impressing and dispensing means While said carrier segment is in contact with said storage means segment.

17. The copying machine of claim 14 including means for deactivating said impressing means and repetitively transporting said storage means segment past said dispens ing means, whereby multiple copies may be produced from a single image exposure.

References Cited UNITED STATES PATENTS 3,199,086 8/1965 Kallmann 340-173 JOHN M.-HORAN, Primary Examiner US. Cl. X.R. 

